Survival

Juvenile Survival

Juvenile Stage: Effects of Predation — Experiments were conducted in large tanks in the stream side research facility to estimate survival (mean ± 1 SE) of  juvenile lake sturgeon at 2 ages with and without  alternate prey species (a species of minnow) when exposed to different predator species.

Methodology

 

  • 3 Age Classes (8, 13, 16 Weeks)
  • Predator allowed to acclimate for 24 hours
  • 3 substrates were used
    –  Sturgeon introduced
    –  Distribution and mortality were followed
Substrate Chart

 

Predation Rate Chart

 

Rock Bass

 

Smallmouth Bass

 

Crayfish

 

 

Pike

Lake sturgeon predation rates were highest by crayfish.

 

 

Focusing on comparisons between just large mouth bass and crayfish, large mouth bass appear to eat minnows but not sturgeon. However, crayfish kill sturgeon at both ages with and without other prey available.  Sturgeon predation by crayfish is likely a major source of mortality and is likely due to the fact that sturgeon live on the river and lake bottom and are easier for crayfish to catch than are minnows.Survival Chart

 

Juvenile Stage: Over-Wintering

Over Winter Map

 

 

 

 

 

 

 

 

Ultrasonic telemetry was used to quantify juvenile over-winter survival.  40 individuals (20 from 2 rearing locations) were equipped with telemetry tags and followed during the following spring.  We recovered 16 of 40 live suggesting that over-winter juvenile survival during the first year of life was 40% (Crossman et al. 2010).

 

Movements of Juvenile Sturgeon Following the First Winter of Life (Crossman et al., 2010)

Juvenile Movements Table

 

 

 

 

Large mesh gill net surveys are used as assessment tool to monitor survival of juvenile lake sturgeon of different year classes following release. In caption A DNR and MSU biologists use a device to determine if a juvenile fish has a coded wire tag implanted which would indicate hatchery origin. Caption B shows biologists checking nets for sturgeon. Caption C shows a holding tank on the boat where fish are kept until measurements are taken.

 

 

 

Juvenile Monitoring

 

Juvenile Monitoring

 

Juvenile Monitoring